It may be difficult for the clinician to intuitively determine a deformation of a portion of an anatomical structure by visually comparing two different medical images.
A publication “Computational anatomical methods as applied to ageing and dementia” by P. M. Thompson et al., published in The British Journal of Radiology, volume 80, 2007, pp. 78-91, describes tensor-based morphometry, which is said to be able to track volumetric changes throughout a brain of a patient. If a pair of scans is collected from the same subject over time, they can be aligned with each other, using a fluid transformation that applies compressions and expansions at a local level throughout the anatomy. So long as the matching is accurate, the spatial gradient of the transformation, which takes the form of a deformed grid, measures how much tissue is lost over the time interval between the scans. The deformed grid can be plotted and colour-coded. Applied to a sequence of scans acquired over time from the same patient, these deformed grids or voxel compression maps, also known as Jacobian maps, can reveal the extent and spread of atrophy.
Said tensor-based morphometry thus allows a clinician to obtain a plotted and colour-coded visualization of deformed portions of the brain of the patient.